Grinding wheel dressing device



Aug. 4, 1964 K. ZWICK GRINDING WHEEL DRESSING DEVICE Filed April 10, 1963 United States Patent O M 3,143,106 GRINDING WHEEL DRESSING DEVICE Kurt Zwiclr, Munich, Germany, assignor to Feinmechanik G.nr.b.H., Weilheim, Germany, a company of Germany Filed Apr. 10, 1963, Ser. No. 272,064 Claims priority, application Germany Apr. 25, 1962 7 Claims. (Cl. 125-11) This invention relates to the dressing and shaping of abrasive grinding wheels, and more particularly to a device for dressing and shaping the radial face of a grinding wheel so as to form a narrow axially projecting rim.

A common task in the preparation of tool bits from cylindrical steel stock is the grinding of a flat face in an axial plane of the bit so that the remaining tool bit portion has a sernicylindrical shape. The flat tool bit face is ground on the radial face of a generally cylindrical abrasive wheel. If the grinding wheel makes simultaneous contact with the tool bit over the entire axial length of the flat, the heat generated by friction may be sufficient to affect the temper of the tool bit. It is therefore conventional to recess the central portion of the radial grinding wheel face in such a manner as to leave an axially projecting narrow rim. When only the narrow grinding wheel rim is in frictional contact with the tool bit, relatively little heat is generated, and is readily dissipated from the surface of the tool bit.

Because the grinding action is concentrated on the narrow rim, grinding wheels of the type described must be dressed relatively frequently. The dressing devices heretofore available for this purpose rely on the skill of the operator for guiding the dressing tool. It is diflicult even for an experienced mechanic to produce a rim whose radial width is small enough to prevent overheating of the tool bit while being as great as is permissible so that the number of dressing operations is limited to The known dressing devices make it possible to reduce the width of the grinding wheel to such an extent that the remaining projecting face is either useless or so narrow as to require redressing after a very short operation.

An object of the invention is the dressing of a radial wheel face in such a manner that a peripheral rim of predetermined width can be produced even by a relatively inexperienced mechanic.

Another object is the shaping of a rim of precisely reproducible width in successive dressing operations on the same wheel.

Other objects and many of the attendant advantages of this invention will become apparent from the following detailed description of preferred embodiments thereof when taken in conjunction with the attached drawing in which:

FIG. 1 is a fragmentary side-elevational and partly sectional view of a grinding machine equipped with a wheel dressing device of the invention;

FIG. 2 shows the apparatus of FIG. 1 in front elevation;

FIG. 3 is a sectional fragmentary plan view of the apparatus of FIG. 1;

FIG. 4 shows a modified embodiment of the invention in a view corresponding to FIG. 2;

FIG. 5 is a sectional plan view of the device of FIG. 4;

FIG. 6 shows another grinding machine equipped with a dressing device of the invention in fragmentary front elevation; and

FIG. 7 illustrates the apparatus of FIG. 6- in plan view.

Referring now to the drawing in detail, and initially to FIG. 1, there is seen the supporting frame 10 of a grinding machine. Bearings 11, 12 on the frame 10 rotatably support a drive shaft 16 on which a V-belt pulley 14 is mounted. A splined free end of the shaft 16 con- 3,143,106 Patented Aug. 4., 1964 Ice formingly engages a coaxial grinding wheel shaft 18. The grinding wheel shaft is rotatable and capable of axial movement in the frame 10 as indicated by a double arrow.

A cup shaped abrasive grinding wheel 20 is releasably fastened to the grinding wheel shaft in a conventional manner by fastening means of which only a flange 21 on the shaft 18 is illustrated in the drawing. Axial movement of the shaft 18 is actuated by a bearing 22 in which the shaft is axially secured. A radially projecting lug 24 on the bearing 22 has a threaded bore parallel to the common axis of the shafts 16, 18 which is engaged by the threaded end portion 26 of a spindle 28 rotatable in the frame 10 but secured against axial movement. A knurled knob 38 is provided for turning the spindle, and for thereby axially shifting the grinding wheel 20.

The dressing tool is a metal rod 32 from which a diamond 34 projects in an axial direction. The rod 32 is attached to a carrier arm 36 by means of a set screw 56 as better seen in FIG. 2. The arm 36 is secured to a heavy pivot pin 38 on the frame 10. Pivoting movement of the arm 36 on the pin 38 moves the rod 32 and diamond 34 radially toward and away from the axis of rotation of the wheel 20.

Radially outward movement of the dressing tool is limited by cooperating abutment means on the arm 36 and on the stationary frame 10. The abutment means on the arm 36 have been omitted from FIG. 2 for the sake of clarity. The abutment means on the frame 10 consist of a stepped disk 40 of basically circular across section which is rotatable on the frame about an axis parallel to the axis of the Wheel 20, and is held in a selected angular position by friction. A step portion 44 of the disc 40 is eccentric with respect to the disc axis.

As shown in FIG. 3, the disc 40 has a knurled rim 42 by means of which it may be turned about its axis. A retractable pin 46 having a head 48 and located between the set screw 56 and the pivot pin 38 constitutes the abutment means on the arm 36. During outward radial movement of the dressing tool, the pin 46 eventually abuts against the cylindrical face of the eccentric step portion 44 of the disc 40, and thereby limits the dressing tool movement in a radial plane.

The afore-described apparatus is operated as follows:

A cup shaped grinding wheel 20 is fastened to the shaft 18 by means of the fixed flange 21 and of a nonillustrated loose flange and axial bolt on the shaft 18, as is usual. The dressing tool is fastened in a suitable axial position on the arm 36 by means of the set screw 56 which engages the rod 32 and holds the tool in such a position that it extends toward the wheel 20 through a guiding passage 58 in the frame structure. The pulley 14 is connected to a source of driving power, and the wheel 20 is thereby rotated. The arm 36 is moved manually toward and away from the limiting position defined by abutment of the pin 46 against a peripheral portion of the disk 40 while the grinding wheel 20 is gradually fed in an axial direction toward the dressing tool by manual rotation of the knob 30.

The annular radial face' 50 of the grinding wheel is thereby axially recessed in such a manner as to leave an axially projecting rim 90. The width of the rim may be adjusted by turning the rim 42 of the disk 40. The manner in which the rim 90 is employed to grind a flat axial face on a tool bit 1 is indicated in FIG. 3. The conventional devices which secure the tool 1 on the frame 10 during grinding have not been shown since they may be conventional and are not directly relevant to this invention.

If the rim 90 should wear down unevenly during use, it is preferred to grind a flat face on the wheel 20 prior to shaping the central recess, and such a flat face may be desirable for other grinding tasks. For this purpose,

the pin 46 is axially withdrawn by means of its head 48 so that it clears the disc 40, and the arm 36 may be freely pivoted about the pin 38. The abutment pin 46 is spring biased toward the operative position shown in FIG. 3 and equipped with a stop to hold it in the retracted inoperative position against the force of the spring as will be discussed hereinafter with reference to the abutment 68 in FIG. 7.

The embodiment of the invention shown in 'FIGS. 4 and 5 differs from that described hereinabove by the abutment means provided on the grinding machine frame 10. An abutment screw 52- is threadedly movable in a stud 54 on the frame in. a direction which is approximately tangential with respect to a circle drawn about the axis of the pivot pin 38 through the tip of the pin 46. The limit of outward radial move-ment of the dressing tool 32, 34 may be adjusted by turning the screw 52. When the pin 46 is retracted into its inoperative position, it clears the screw 52, and the dressing tool may be employed to grind a flat radial face on the wheel 20.

In the devices shown in FIGS. 1 to 5, the diamond 34 moves in a fixed radial plane during the dressing operation, and the wheel 20 is moved axially with respect to the radial plane. The grinding wheel dressing devices illustrated, however, may be readily modified for axial movement of the dressing tool relative to a grinding wheel whose axial position is fixed. A third embodiment of the dressing device of the invention is shown in FIGS. 6 and 7 in its cooperation with a grinding wheel that rotates in a fixed plane.

The frame 10' of the grinding machine illustrated in FIGS. 6 and 7 has a Wheel shaft 18 rotatably mounted thereon. The wheel shaft carries the pulley 14 by means of which motive power is transmitted to the cup shaped grinding wheel 20 mounted on the shaft 18. The shaft 18' is axially secured in the frame It) by a bearing sleeve 19.

A pivot pin 60 is secured on the frame 10', and supports a tool-carrying bellcrank lever 62. A dressing tool consisting of a bar 32 with a diamond 34 is attached to the free end of one arm 64 of the lever 62. The other arm 66 carries a retractable abutment 68. The abutment 68 consists of a pin 70 to move in a bore 76 of the lever arm 66 toward the frame 10'. The axial end portion of the pin 70 adjacent the frame is cylindrically enlarged, and the other axial end portion carries a knurled head 74. A stop pin 80 projects from the head 74 toward the lever arm 66. The pin 80 engages a corresponding recess in the arm 66, and thus permits the spring 78 to hold the pin 70 in the illustrated operative position. When the head 74 is pulled away from the arm 66 against the force of the spring 76, turned about its axis, and released, the tip of the stop pin 80 abuts against the surface of the arm 66, and the enlarged end portion of the abutment pin 70 is withdrawn into the bore 76 to make the abutment 68 inoperative.

The abutment 68 cooperates with an abutment disc 82 on the frame 10' which may be angularly displaced about its axisby means of a knurled rim 84. The disc 82 has an end face which is helical about the disc axis. The enlarged end portion of the pin 70 abuts against a peripheral portion of the helical disc face when the dressing tool is moved away from the axis of rotation of the Wheel 20. The limit of outward dressing tool movement may be adjusted by turning the disk about its axis. The disk 82 remains outside the path of the pin 70 in the inoperative position of the abutment 68.

The dressing tool shown in FIGS. 6 and 7 is movable relative to the frame 10' in the direction of the axis of the wheel 20. Such movement is actuated by rotation of a knurled knob 86 which cooperates with a threaded member (not shown) within a sleeve 85 on the frame 16 to axially shift the pivot pin 60.

It will be appreciated that the dressing device shown in FIGS. 6, 7 may be used to dress an axially movable grinding wheel in the manner shown in FIGS. 1 to 5. Obviously, many other modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A grinding wheel dressing arrangement comprising,

in combination:

(a) a support;

(12) shaft means rotatable on said support about an axis of rotation;

(c) fastening means for fastening a grinding Wheel to said shaft for rotation therewith in a radial plane;

(d) a dressing tool carrier mounted on said support for movement of a portion of said carrier transverse of said axis;

(e) attaching means on said carrier for attaching a dressing tool to said carrier portion in dressing engagement with a grinding wheel fastened to said shaft; and

(f) abutment means for limiting movement of. said dressing tool in a direction away from said axis during said transverse movement of said dressing tool carrier,

(1) said carrier being a lever having two arms, a portion of said carrier intermediate said arms being pivotally fastened to said support, said attaching means being mounted on one of said arms, and said abutment means including two engageable abutment members, one of said abutment members being mounted on said support, and the other abutment member being mounted on the other arm of said lever.

2. A grinding wheel dressing arrangement comprising,

in combination:

(a) asupport;

(b) shaft means rotatable on said support about an axis of rotation;

(c) fastening means for fastening a grinding wheel to said shaft for rotation therewith in a radial plane;

(d) a dressing tool carrier mounted on said support for movement of a portion of said carrier transverse of said axis;

(2) attaching means on said carrier for attaching a dressing tool to said carrier portion in dressing engagement with a grinding wheel fastened to said shaft; and

(f) abutment means for limiting movement of said dressing tool in a direction away from. said axis during said transverse movement of said dressing tool carrier,

(1) said abutment means including two abutment members respectively mounted on said carrier and on said support, one of said members including a disk rotatable about an eccentric axis, the other member being arranged for movement toward said eccentric axis when said dressing tool moves away from said axis of rotation.

3. A grinding wheel dressing arrangement comprising,

in combination:

(a) asupport;

(b) shaft means rotatable on said support about an axis of rotation;

(c) fastening means for fastening a grinding wheel to said shaft for rotation therewith in a radial plane;

(d) a dressing tool carrier mounted on said support for movement of a portion of said carrier transverse of said axis;

(e)' attaching means on said carrier for attaching a dressing tool to said carrier portion in dressing engagement with a grinding wheel fastened to said shaft; and

(f) abutment means for limiting movement of said dressing tool in a direction away from said axis during said transverse movement of said dressing tool carrier,

(1) said abutment means including two abutment members respectively mounted on said carrier and on said support, one of said members being mounted for threaded movement about an axis, the other member being arranged for movement in the direction of said axis of threaded movement when said dressing tool moves away from said axis of rotation.

4. A grinding wheel dressing arrangement comprising,

in combination:

(a) asupport;

(b) shaft means rotatable on said support about an axis of rotation;

(c) fastening means for fastening a grinding wheel to said shaft for rotation therewith in a radial plane;

(d) a dressing tool carrier mounted on said support for movement of a portion of said carrier transverse of said axis;

(e) attaching means on said carrier for attaching a dressing tool to said carrier portion in dressing engagement with a grinding wheel fastened to said shaft; and

(f) abutment means for limiting movement of said dressing tool in a direction away from said axis during said transverse movement of said dressing tool carrier,

(1) said abutment means including two abutment members respectively mounted on said carrier and on said support, one of said members being mounted for angular movement about an axis, and having a helical abutment face about said axis of angular movement, the other member being mounted for abutment against a peripheral portion of said abutment face when said dressing tool moves in a direction away from said axis of rotation.

5. A grinding wheel dressing arrangement comprising,

in combination;

(a) a support;

(b) shaft means rotatable on said support about an axis of rotation;

(c) fastening means for fastening a grinding wheel to said shaft for rotation therewith in a radial plane;

(d) a dressing tool carrier mounted on said support for movement of a portion of said carrier transverse of said axis;

(e) attaching means on said carrier for attaching a dressing tool to said carrier portion in dressing engagement with a grinding Wheel fastened to said shaft;

(1) abutment means for limiting movement of said dressing tool in a direction away from said axis during said transverse movement of said dressing tool carrier; and

(g) actuating means connected to said abutment means for moving the same between an operative and an inoperative position,

(1) said abutment means when in said operative position thereof being effective to limit said movement of said dressing tool in said direction, and said abutment means when in said inoperative position permitting unlimited movement of said dressing tool,

(2) said actuating means including yieldably resilient means permanently urging said abutment means toward said operative position thereof.

6. An arrangement as set forth in claim 5, wherein said abutment means include two abutment members respectively mounted on said support and on said carrier, one of said members being connected to said actuating means for movement thereby between an operative position thereof in which said one member abuts against the other abutment member when said dressing tool moves away from said axis of rotation, and an inoperative position in which said other abutment member is spaced from the path of said one abutment member during the movement of said dressing tool in said direction.

7. An arrangement as set forth in claim 6, further comprising manually operable stop means for holding said one abutment member in said inoperative position thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,512,608 Knowles Oct. 21, 1924 1,513,757 Hanson Nov. 4, 1924 2,435,234 Munro Feb. 3, 1948 2,723,497 Grobey Nov. 15, 1955 2,914,057 Abadjieif Nov. 24, 1959 2,928,384 Slupecki Mar. 15, 1960 FOREIGN PATENTS 218,433 Switzerland Apr. 1, 1942 

1. A GRINDING WHEEL DRESSING ARRANGEMENT COMPRISING, IN COMBINATION: (A) A SUPPORT; (B) SHAFT MEANS ROTATABLE ON SAID SUPPORT ABOUT AN AXIS OF ROTATION; (C) FASTENING MEANS FOR FASTENING A GRINDING WHEEL TO SAID SHAFT FOR ROTATION THEREWITH IN A RADIAL PLANE; (D) A DRESSING TOOL CARRIER MOUNTED ON SAID SUPPORT FOR MOVEMENT OF A PORTION OF SAID CARRIER TRANSVERSE OF SAID AXIS; (E) ATTACHING MEANS ON SAID CARRIER FOR ATTACHING A DRESSING TOOL TO SAID CARRIER PORTION IN DRESSING ENGAGEMENT WITH A GRINDING WHEEL FASTENED TO SAID SHAFT; AND (F) ABUTMENT MEANS FOR LIMITING MOVEMENT OF SAID DRESSING TOOL IN A DIRECTION AWAY FROM SAID AXIS DURING SAID TRANSVERSE MOVEMENT OF SAID DRESSING TOOL CARRIER, (1) SAID CARRIER BEING A LEVER HAVING TWO ARMS, A PORTION OF SAID CARRIER INTERMEDIATE SAID ARMS BEING PIVOTALLY FASTENED TO SAID SUPPORT, SAID ATTACHING MEANS BEING MOUNTED ON ONE OF SAID ARMS, AND SAID ABUTMENT MEANS INCLUDING TWO ENGAGEABLE ABUTMENT MEMBERS, ONE OF SAID ABUTMENT MEMBERS BEING MOUNTED ON SAID SUPPORT, AND THE OTHER ABUTMENT MEMBER BEING MOUNTED ON THE OTHER ARM OF SAID LEVER. 